Communications System Density and Range Improvement by Signal-Strength-Directed Channel Class Selection with Weighting for Minimum Capacity Consumption

ABSTRACT

Methods and apparatuses for optimized channel selection are disclosed. In one example, a channel quality is measured of each channel of an available number of channels on which a mobile communication device can transmit and receive. A subset of the available number of channels is allocated to a long range channel class responsive to the channel quality. An RSSI of the mobile communication device is monitored and correlated to a mobile communication device proximity to a base station. A channel is selected from the long range channel class if the mobile communication device proximity is greater than a predetermined proximity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. Utility application Ser. No.12/782,940, filed May 19, 2010, entitled “Communications System Densityand Range Improvement by Signal-Strength-Directed Channel ClassSelection with Weighting for Minimum Capacity Consumption,” which isincorporated herein by reference in its entirety for all purposes.

BACKGROUND OF THE INVENTION

Radio communication systems have limitations with respect to the numberof users which can be active in a given geographic area. The limitationsdepend on the size of the geographic area, the propagation losses in thearea, the statistics for usage-period duration and interval, anysystem-idle background usage, and the radio communication systemphysical parameters.

How particular types of radio systems handle too many users varies. Inone prior art digital enhanced cordless telecommunications (DECT)system, in cases where usage is carrier-to-interferer limited, thesystem may offer reduced range for acceptable audio quality.Alternatively, the system may refuse to allow new links to beestablished in cases where usage for a particular channel and timeslotcombination is allowed only if interference in that combination is lowerthan a threshold, and that threshold is exceeded by the propagatinginterfering signal from a not-so-distant user in another communicationslink.

The density of users the system can handle trades off with range due toother-user interference imposing a noise floor for the radio signal'sSNR. In the prior art, a variety of attempts to address the range vs.density problem have been tried. In one prior art attempt, the transmitpower of the unit is adjusted in response to the received signal level.For this approach, at strong received signal levels the transmit signalis reduced. The success of this approach is limited by the fact that ifthe individual units are interference-limited in range even at lowpower, and for a system where all units are at the same power level, itdoes not matter what the actual power level is, as the receiver'ssignal-to-interference level is the same. Units which are at a rangewhere they are no longer at low power are a degradation to theall-units-at-the-same-power case. Adjusting transmit power in responseto received signal level works to improve density only if most unitsadjust their transmit power downwards far enough that range is limitedby signal-to-thermal-noise rather than signal-to-interference. This iscommonly not the case for a non-line-of-sight environment such as ahead-worn product where the user can shadow the antenna path between thebase and headset even at close range.

As a result, improved methods and apparatuses for improved range anddensity are needed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings,wherein like reference numerals designate like structural elements.

FIG. 1 illustrates a radio communication system with multiple basestations and mobile communication devices.

FIG. 2 illustrates a simplified block diagram of a mobile communicationdevice.

FIG. 3 illustrates an FCC part 15 subpart D-compliant DECT 6.0 channeland frame structure in one example.

FIG. 4 illustrates assignment of a subset of channels to a long rangechannel class in one example.

FIG. 5 illustrates ranking available channels in an ordered preferencelist based on noise level.

FIG. 6 is a flow diagram illustrating a channel selection process for amobile communication device in one example.

FIG. 7 is a flow diagram illustrating a channel selection process for amobile communication device in a further example.

FIG. 8 illustrates a usage scenario for optimized channel selectionwhere a mobile communication device transitions between selection of achannel from a short range channel class and a long range channel class.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Methods and apparatuses for radio system channel selection aredisclosed. The following description is presented to enable any personskilled in the art to make and use the invention. Descriptions ofspecific embodiments and applications are provided only as examples andvarious modifications will be readily apparent to those skilled in theart. The general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the invention. Thus, the present invention is to be accorded thewidest scope encompassing numerous alternatives, modifications andequivalents consistent with the principles and features disclosedherein. For purpose of clarity, details relating to technical materialthat is known in the technical fields related to the invention have notbeen described in detail so as not to unnecessarily obscure the presentinvention.

This invention relates to optimized channel selection in ensemble radiocommunication systems whose capacity to provide user-density is finite.In the prior art, it is common for systems to choose the leastinterfered channel when selecting a channel and timeslot to operate in.This ensures that each additional user in a dense system gets an equalamount of the available capacity. The inventor has recognized that usersdon't need equal amounts of capacity: an individual unit which is beingoperated at close range does not need as much capacity as a unit whichis being operated at long range, capacity being a function of bandwidthneeded and available radio channel signal-to-interference ratio. Optimumdensity is instead achieved by each unit consuming only as much capacityas it needs.

Methods and systems are described for optimized management of a radiocommunications system consisting of multiple users in an environmentwhere user-density is large enough to limit range, but where not allusers need long-range communications at the same time. In one example, adensity installation consists of multiple timeslotted communicationssystems incorporating shared multiple channels but withasynchronous-from-unit-to-unit timeslotting. The units select operatingchannels and timeslots from time to time based on some channel selectionalgorithm, commonly based on the observation of existing interference,the algorithm segregating a group of channels from the total availabledesignated for the purpose of description as the long range classchannels. Individual units select to not use channels from thesegregated long range channel class unless the observed received signalstrength indication (RSSI) for the desired communications signalreceived from the other end of the communications link would indicatethat the unit is at long range from the other end of the communicationslink.

In one implementation, the sample-to-sample variation of RSSI isanalyzed in addition to its average or instant level so as to attempt tofurther qualify range, where the RSSI is more variable sample-to-samplewhen range increases. For longer propagation paths, even if it shouldhappen that a set of samples in an average are higher than would benormally indicated for a long range due to statistical variation, theRSSI has a larger average variance.

In one implementation, certain channels are optimized for long-range useby having units from time to time observe the other-user (interferencesignal) RSSI on channels in a preference order rather than grouped as“long range class” or “not long range class”. A channel is selected foruse by using both the desired-service RSSI value with the rankedobserved interference RSSI on the available channels, and selecting achannel and timeslot based on the preference order and the observedinterference RSSI and the observed desired-service RSSI such that thechannel and timeslot selected is the first channel in the preferenceorder having an available timeslot which will offer acceptableperformance for the measured desired-service and interference-servicelevels. In this manner, channels at the end of the preference order areautomatically made available for users who need long range, each radiounit having selected a channel for which that unit's communications linkdoes not use capacity available to the ensemble of units in excess ofthat unit's communications link's needs. In this way an automaticadjustment of the size of the long range class allocation of channelsoccurs as individual units change range, and neither long range norshort-range units experience an unbalanced excess or deficit ofavailable capacity.

Thus, channel selection is optimized so that cleaner channels (channelswith lower interference levels) are available for some users to get longrange with. Users who don't need the cleanest channels are packedtogether in some channels where there will be higher interference, butinterference is not an issue because these users are not operating atlong range. This then leaves some channels with reduced interferenceavailable for users who do need long range. Having systems beingoperated at short-range choose channels where there is just low enoughinterference to operate properly assures that other channels can be freefor long-range use.

In one example usage implementation, this allows units to be operated atthe maximum DECT range in an area which is close to but not at thedensity limit for systems operating at short range. For example, in theprior art, only short “in cubicle” range for density applications may beoffered even though roaming ten to twenty times that short range ispossible if the channel is clean. There are no available clean channelsin a density installation where each new unit chooses the cleanestavailable though, so delivered range in a density installation is short.Adopting the methods and systems described herein allows long-rangeservice even in a dense installation where the number of long-rangeusers is small relative to the total number of users. In one example,small being, for the case of DECT 6.0, ⅕^(th) of the totalnon-frequency-reusing users in a reuse area, for instance, with a singlechannel in a designated long range class.

In one example, a method of channel selection for a mobile communicationdevice includes measuring a channel quality of each channel of anavailable number of channels on which the mobile communication devicecan transmit and receive. A subset of the available number of channelsis allocated to a long range channel class responsive to the channelquality. The method includes monitoring an RSSI for the desiredcommunications link of the mobile communication device, and correlatingthe desired-signal RSSI of the mobile communication device to a mobilecommunication device's proximity to a base station. A channel isselected from the long range channel class if the mobile communicationdevice proximity is greater than a predetermined proximity.

In one example, a method of channel selection for a mobile communicationdevice includes periodically performing a channel quality measurementfor each channel of an available number of communication channels andmonitoring desired and undesired signal RSSIs at the mobilecommunication device. The lowest quality channel satisfying apredetermined required signal to interference ratio is identifiedutilizing the desired and undesired signal RSSIs at the mobilecommunication device and the channel quality measurement for eachchannel. The lowest quality channel satisfying the predeterminedrequired signal to interference ratio is selected.

In one example, a mobile communication device includes a processor, atransceiver, and an antenna. The mobile communication device includes amemory storing a channel selection optimization application configuredto allocate a subset of available channels to a long range channelclass, where the channel selection optimization application isconfigured to select the channel from the long range channel class ifthe mobile communication device desired-signal RSSI indicates the mobilecommunication device is at long range. For example, the mobilecommunication device may be a headset having a DECT transceiver wherethe selectable channels are DECT channels.

In one example, a mobile communication device includes a processor, atransceiver, an antenna, and a memory storing a channel selectionoptimization application configured to identify a lowest quality channelsatisfying a predetermined required signal to interference ratioutilizing the RSSI of the mobile communication device and a channelquality measurement for each available channel of an available number ofchannels.

FIG. 1 illustrates a radio communication system 100 with multiple basestations and mobile communication devices in one example. The radiocommunication system 100 may, for example, be implemented in a telephonecall center or an office environment having a high density of users.Base station 2, base station 4, base station 6, base station 8, and basestation 10 are in radio communication with mobile communication device12, mobile communication device 14, mobile communication device 16,mobile communication device 18, and mobile communication device 20,respectively.

In one example, radio communication system 100 is a TDMA system, such asthat utilized by the DECT protocol. In general, a carrier frequency in afrequency band is used by a base station in radio contact with a mobilecommunication device. For example, a base station 10 transmits to amobile communication device 20 in a transmit time slot in a first frameon a selected carrier frequency. The mobile communication device 20transmits to the base station 10 in a receive time slot in a secondframe on the same selected carrier frequency. Thus, during transmit timeslots, base station 10 acts as a transmitter and during receive timeslots base station 10 operates as a receiver. The first frame and thesecond frame taken together form a duplex frame.

Base stations 2, 4, 6, 8, and 10 may, for example, be a landline phone,access point (AP), personal computer, USB dongle, or mobile phone. Basestations 2, 4, 6, 8, and 10 are coupled to a telecommunications network.The network may be a communications network which may include a publicswitched telephone network (PSTN), a cellular network, an integratedservices digital network (ISDN), a local area network (LAN), and/or awireless local area network (WLAN), that support standards such asEthernet, 802.11, and/or voice over internet protocol (VoIP).

In one example, the access point includes a transceiver and a processorconfigured to allow a wireless device (e.g., one of the mobilecommunication devices 12, 14, 16, 18, and 20) access to a networkconnected to the access point (e.g., via a 10/100 Ethernet RJ-45 port).The access point may be any device that allows wireless-equippedcomputers and other devices to communicate with a wired network. In oneexample, the access point is able to support the 802.11a, 802.11b,and/or 802.11g wireless networking standards. In other examples, theaccess point may be able to support other wireless networking standards.

The received signal strength indicator (RSSI) of other-user anddesired-signal wireless links 22 are measured and monitored over timeand processed to determine which channel to operate the mobilecommunication device 20. The RSSI measurements can be monitored eitherat the mobile communication device 20 or at the base station 10, orboth. If measured and monitored at the base station 10, the mobilecommunication device 20 can be configured to query the base station 10as to what the interference-signal and desired-signal RSSIs are. Ifmeasured and monitored at the mobile communication device 20, the basestation 10 can be configured to query the mobile communication device 20as to what the interference-signal and desired-signal RSSIs are. In oneexample, the RSSI measurements are processed at the mobile communicationdevice 20 to determine the appropriate mobile communication devicechannel. In a further example, the RSSI measurements are processed atthe base station 10 to determine the appropriate mobile communicationdevice channel.

FIG. 2 illustrates a simplified block diagram of a mobile communicationdevice with optimized channel selection. Referring to FIG. 2 inconjunction with FIG. 1, a block diagram of an example of mobilecommunication device 20 is shown. Mobile communication device 20includes a control unit 24 operably coupled to a memory 44, a wirelesstransceiver 34 using an antenna 36, a user interface 38, a speaker 40,and a microphone 42. In one example, wireless transceiver 34 is a DECTtransceiver implementing DECT 6.0.

Control unit 24 allows for processing data, in particular managing RSSIdata between wireless transceiver 34 and memory 44 for determining whichchannel to operate mobile communication device 20. In one example,control unit 24 is a high performance, highly integrated, and highlyflexible system-on-chip (SOC) having signal processing functionality.Control unit 24 may include a variety of processors (e.g., digitalsignal processors), with conventional CPUs being applicable.

Memory 44 may include a variety of memories, and in one example includesSDRAM, ROM, flash memory, or a combination thereof. Memory 44 mayfurther include separate memory structures or a single integrated memorystructure. In one example, memory 44 may be used to store passwords,network and telecommunications programs, and/or an operating system(OS). Memory 44 includes a mobile communication device controlapplication 30 and a user interface application 32. User interface 38allows for manual communication between the device user and the device,and in one example includes an audio and/or visual interface such that aprompt may be provided to the user's ear and/or an LED may be lit.

Memory 44 stores an channel selection optimization application program26 executed by control unit 24 to determine the operating channel of themobile communication device 20. Channel selection optimizationapplication program 26 includes an RSSI analysis engine 28 and channelquality engine 46.

Channel quality engine 46 is configured to measure the quality of eachavailable channel on which the mobile communication device 20 cantransmit and receive data. In one example, the channel quality engine 46is configured to monitor the interference level of each channel. Aconstant scan is performed for interference levels for each time slotand for each carrier. In the DECT band, the process of scanning carriersfor interference levels is set forth in the DECT regulatory protocol. Inthis TDMA system with 10 msec transmit framing, within the transmitframe there are twenty four time slots, with twelve for transmit andtwelve for receive. For any individual time slot interference levels inboth bands are scanned. In one example, a table of interference levelsis created.

In one example, the channel selection optimization application program26 is configured to monitor a proximity utilizing an RSSI valueassociated with a wireless signal received at wireless transceiver 34.Responsive to the proximity and the measured quality of the availablechannels, the channel selection optimization application program 26selects an appropriate channel. For example, the proximity is aproximity between the mobile communication device 20 and the basestation 10. In one example, the proximity is a predetermined proximitydelineating a short range status (e.g., near status) or a long rangestatus (e.g., far status) of the mobile communication device 20 from thebase station 10.

Utilizing RSSI analysis engine 28, channel selection optimizationapplication program 26 is operable to process a plurality of RSSIvalues. In one example, a time weighted average of RSSI values isidentified and compared to a threshold RSSI to determine proximity.Memory 44 may store RSSI values and predetermined threshold RSSI valuesfor use by channel selection optimization application program 26 todetermine the proximity utilized in determining the operating channel ofmobile communication device 20. The channel selection optimizationapplication program 26 may implement a variety of algorithms to processthe RSSI data and select the desired channel.

In one example, the channel selection optimization application program26 is configured to allocate a subset of available channels to a longrange channel class, where the channel selection optimizationapplication program 26 is configured to select the channel from the longrange channel class if the mobile communication device RSSI indicatesthe mobile communication device 20 is at long range. For example, themobile communication device 20 may be a headset having a DECTtransceiver where the selectable channels are DECT channels. Where theDECT transceiver implements DECT 6.0, the available number of channelsis five.

In one example, the mobile communication device RSSI indicates themobile communication device 20 is at long range if the mobilecommunication device desired-signal RSSI is below a threshold RSSI. Thethreshold RSSI is associated with a predetermined desired proximitybetween the mobile communication device 20 and the mobile communicationdevice base station 10. In a further example, the channel selectionoptimization application program 26 is configured to determine if themobile communication device RSSI indicates the mobile communicationdevice 20 is at long range in part by observing a sample to samplevariation of the mobile communication device desired-signal RSSI.

In one example, the channel selection optimization application program26 is configured to rank the available channels in order of quality andallocate a predetermined number of channels having the highest qualityto the long range channel class. In one example, the channel selectionoptimization application program 26 is configured to allocate a subsetof the available number of channels to a short range channel class,where each channel of the available number of channels is allocated toeither the short range channel class or the long range channel class.

In a further example, the channel selection optimization applicationprogram 26 is configured to identify a lowest quality channel satisfyinga predetermined required signal to noise ratio utilizing thedesired-signal and undesired interference-signal RSSIs at the mobilecommunication device 20 and a channel quality measurement for eachavailable channel of an available number of channels.

In one example, the channel selection optimization application program26 is further configured to order the available number of channels in apreference order list based on the channel quality measurement, thechannels ranked from lowest quality to highest quality. The channelselection optimization application program 26 identifies a lowestquality channel satisfying a predetermined required signal to noiseratio by computing a measure of the desired-signal andinterference-signal RSSIs and comparing the result of the computation tothe channel quality measurement for each channel in the preference orderlist in increasing order from lowest quality to highest quality.

FIG. 3 illustrates a DECT channel and frame structure in one example. Inthe example illustrated in FIG. 3, a United States DECT 6.0 system isillustrated. There are five channels 48 having 1,728 kHz spacingavailable for use by the system, channels CH0, CH1, CH2, CH3, and CH4.The frequency band of operation is 1920 MHz-1930 MHz. One of ordinaryskill in the art will recognize that where other DECT systems areutilized, such as those in Europe, these figures will vary. For example,in Europe, ten carriers are utilized in the frequency band 1880 MHz-1900MHz. There are twenty four timeslots 50 per frame, including twelve timeslots in a down link direction (i.e., base station 10 to mobilecommunication device 20) followed by twelve slots for the up linkdirection (i.e., mobile communication device 20 to base station 10). Atimeslot 50 is 416.7 microseconds long, or 480 bit periods where theinstantaneous data rate is 1.152 Mbits/sec.

FIG. 4 illustrates assignment of a subset of channels to a long rangechannel class in one example. Channel CH0 has a measured interferenceINT 0, channel CH 1 has a measured interference INT 1, channel CH 2 hasa measured interference INT 2, channel CH 3 has a measured interferenceINT 3, and channel CH 4 has a measured interference INT 4.

In this example, interference INT 0, INT 1, and INT 4 are the highestinterference levels and interference INT 2 and INT 3 are the lowestinterference levels. As a result, channel CH 2 and channel CH 3 areallocated to a long range channel class 54, and channel CH 0, channel CH1, and channel CH 4 are allocated to a short range channel class 52. Ina further example, short range channel class 52 may be subdivided intoadditional channel classes.

FIG. 5 illustrates ranking available channels in an ordered preferencelist based on noise level. In the example shown in FIG. 5, a lookuptable 500 has been generated containing an ordered list of channels 502and their associated interference level 504. The lookup table 500 isordered based on the measured interference 504 of each channel 502. Thechannels are ordered from lower quality to a higher quality, with thechannels having the lowest noise appearing at the bottom of lookup table500.

Channel CH 0 has a measured interference INT 0, channel CH 1 has ameasured interference INT 1, channel CH 2 has a measured interferenceINT 2, channel CH 3 has a measured interference INT 3, and channel CH 4has a measured interference INT 4. In the example shown in FIG. 5, INT1>INT 0>INT 4>INT 3>INT 2. As a result, the channels appear in lookuptable 500 in the order CH 1, CH 0, CH 4, CH 3, and CH 2.

FIG. 6 is a flow diagram illustrating a channel selection process for amobile communication device in one example. At block 602, the channelquality of all channels is measured. At block 604, the highest qualitychannels are identified. At block 606, a predetermined number of highestquality channels are allocated to a long range channel class. In oneexample, allocating a subset of the available number of channels to along range channel class responsive to the channel quality comprisesranking the channels in order of quality and allocating thepredetermined number of channels having the highest quality to the longrange channel class. In one example, the method further includesallocating a subset of the available number of channels to a short rangechannel class, wherein each channel of the available number of channelsis allocated to either the short range channel class or the long rangechannel class.

At block 608, the desired-signal RSSI of the mobile communication deviceis monitored. At block 610, the mobile communication device'sdesired-signal RSSI is correlated to a proximity to the mobilecommunication device base unit. In one example, correlating thedesired-signal RSSI of the mobile communication device to a mobilecommunication device proximity to a base station comprises observing asample to sample variation of RSSI. In one example, correlating the RSSIof the mobile communication device to a mobile communication deviceproximity to a base station comprises comparing the RSSI to apredetermined threshold RSSI.

At decision block 612, it is determined whether the proximity of themobile communication device is a long range status. The mobilecommunication device is at long range status if it is greater than apredetermined proximity from the base station. If yes at decision block612, at block 616 a channel is selected from the long range channelclass of channels. If no at decision block 612, at block 614 a channelis selected not from the long range channel class.

FIG. 7 is a flow diagram illustrating a channel selection process for amobile communication device in a further example. At block 702, thechannel quality of all channels is measured. The channel qualitymeasurement includes measuring a noise level for each channelperiodically. This noise level may include interference caused by otherDECT users and may be indicated by other-user RSSI.

At block 704, the channels are ranked in a preferred order list fromlowest quality to highest quality. In a further example, the channelsare ranked from highest quality to lowest quality as shown in FIG. 5. Atblock 706, the interference-signal and desired-signal RSSIs at themobile communication device are monitored. At block 708, the lowestquality channel satisfying a predetermined required signal tointerference ratio is identified. For example, identifying the lowestquality channel satisfying a predetermined required signal tointerference ratio involves comparing a measure of the desired-signalRSSI relative to the interference-signal RSSI as a channel qualitymeasurement for each channel in the preference order list in increasingorder from lowest quality to highest quality. At block 710, thisidentified lowest quality channel is selected.

FIG. 8 illustrates a usage scenario for optimized channel selectionwhere a mobile communication device transitions between selection of achannel from a short range channel class and a long range channel class.A system 800 includes a base station 10 and mobile communication device20 capable of wireless communication there between as previouslydescribed. The received signal strength indicator of the desired-signalwireless link 22 is measured and monitored to determine the proximity ofthe mobile communication device 20 from the base station 10.

In system 800, a proximity boundary 806 establishes a range from basestation 10 below which mobile communication device 20 is considered tobe in a NEAR state 810 and beyond which mobile communication device 20is considered to be in a FAR state 812. System 800 utilizes RSSI valuesof signals received over wireless link 22 to determine whether mobilecommunication device 20 is in a NEAR state 810 or FAR state 812.Responsive to this NEAR/FAR determination, mobile communication device20 selects a channel to operate at either from a short range class ofchannels or a long range class of channels. Available operating channelsare allocated to either the short range channel class or the long rangechannel class by measuring interference levels in each channel aspreviously described.

In the example illustrated in FIG. 8, the mobile communication device 20and mobile communication device 802 are located at a proximity greaterthan proximity boundary 806 and therefore select a channel from the longrange class of channels. Mobile communication devices 12, 14, 16, and 18are located at a proximity less than proximity boundary 806 andtherefore select a channel from a short range class of channels. TheNEAR/FAR proximity boundary 806 may be automatically configured or theuser may be set by the user. For example, the user may set the NEAR/FARproximity boundary 806 based upon the density of other mobilecommunication devices in the user's planned device operation area.

While the exemplary embodiments of the present invention are describedand illustrated herein, it will be appreciated that they are merelyillustrative and that modifications can be made to these embodimentswithout departing from the spirit and scope of the invention. Forexample, the number of channels available for use will vary depending onthe radio system implementation. Where a subset of available channelsare allocated to a long range channel class, the size of the subset maybe varied depending upon the particular implementation. Thus, the scopeof the invention is intended to be defined only in terms of thefollowing claims as may be amended, with each claim being expresslyincorporated into this Description of Specific Embodiments as anembodiment of the invention.

What is claimed is:
 1. A method of channel selection for a mobile communication device comprising: periodically performing a channel quality measurement for each channel of an available number of communication channels; monitoring a RSSI of the mobile communication device; identifying a lowest quality channel satisfying a predetermined required signal to interference ratio utilizing the RSSI of the mobile communication device and the channel quality measurement for each channel; and selecting the lowest quality channel satisfying the predetermined required signal to interference ratio.
 2. The method of claim 1, further comprising ordering the available number of communication channels in a preference order list based on the channel quality measurement, the available number of communication channels ranked from lowest quality to highest quality, wherein identifying the lowest quality channel satisfying a predetermined required signal to interference ratio comprises comparing a measure of the desired-signal and interference-signal RSSIs to the channel quality measurement for each channel in the preference order list in increasing order from lowest quality to highest quality.
 3. The method of claim 1, wherein periodically performing a channel quality measurement for each channel comprises measuring an interference level.
 4. The method of claim 3, wherein the noise level is based on interference caused by other DECT users.
 5. The method of claim 1, wherein the mobile communication device transmits and receives on the lowest quality channel utilizing a DECT protocol.
 6. A mobile communication device comprising: a processor; a transceiver; an antenna; and a memory storing a channel selection optimization application configured to identify a lowest quality channel satisfying a predetermined required signal to noise ratio utilizing the RSSI of the mobile communication device and a channel quality measurement for each available channel of an available number of channels.
 7. The mobile communication device of claim 6, wherein the channel selection optimization application is further configured to order the available number of channels in a preference order list based on the channel quality measurement, the available number of channels ranked from lowest quality to highest quality, wherein the channel selection optimization application identifies a lowest quality channel satisfying a predetermined required signal to noise ratio by comparing the a measure of the desired-signal and interference-signal RSSIs to the channel quality measurement for each channel in the preference order list in increasing order from lowest quality to highest quality.
 8. The mobile communication device of claim 6, wherein the transceiver is a DECT transceiver and the available number of channels is five. 